[squid-dev] [PATCH] SBuf const iterator fixes

[Alex Rousskov]

On 02/08/2016 11:18 AM, Amos Jeffries wrote:
> The SBufIterator is mostly actually a const iterator. But not quite.

I am not sure I understand what you are implying because you did not
change any const-related aspects of SBufIterator. What are the
requirements for being a "const iterator" class that old SBufIterator
violated?


> The point of difference from const_iterator is the operator*() API which
> is also different from the normal itertor API in that is returns a char
> instead of a char& or const char &.

Please explain why returning char is wrong for const_iterator. I
understand that [all?] standard iterators return a reference, and I also
understand that a non-const iterator cannot return a char, but I do not
yet understand how that difference affects constant SBufIterator.

Overall, it feels like returning a simple "char" may be more efficient
than forcing the compiler to optimize away references to "char", but I
may be missing something important here.


> This has side effects on the reverse iterator and SBuf begin/end
> methods. Which are also const'ified.

Please note that in the C++11 land, we are supposed to use
cbegin/cend/etc. methods if we unconditionally want a const_iterator.
These are added to the old set of begin/end/etc. methods (half of those
old methods return const_iterators, depending on the object constness
rather than method name):

  http://www.cplusplus.com/reference/list/list/begin/
  http://www.cplusplus.com/reference/list/list/cbegin/

It is up to you whether to add cbegin/cend/etc. methods and whether to
change the caller code to use them.


Thank you,

Alex.